This application claims the benefit of priority under 35 U.S.C. §119 of German Application 10 2015 114 886.2 filed Sep. 4, 2015 the entire contents of which are incorporated herein by reference.
The present invention pertains to a heating device for fluids, which has a tubular jacket surface formed of metal, at least one heating element and at least one control and/or regulating element (control/regulating element) for the at least one heating element, wherein the at least one heating element and the at least one control and/or regulating element are arranged at least partially within the tubular jacket surface formed of metal and are embedded at least partially in a powder or granular material present within the tubular jacket surface formed of metal, and to a method for manufacturing a heating device.
Heating devices for fluids are generally known to be in the form of electric heating cartridges with a control and/or regulating element (control/regulating element). The problem arising in such heating devices is basically that it must be ensured that the temperature, to which the control and/or regulating element is exposed, is as identical as possible to the temperature of the heating device at any time, because a timely intervention of the control or regulating mechanism and especially a timely switching off of the heating device can thus be guaranteed. However, this ideal is not achieved, in practice, so that different temperatures, which lead to a response characteristic that is delayed in time, are present, at least temporarily, at the control and/or regulating element, on the one hand, and at the heating device, on the other hand.
In addition, it is problematic that the prior-art heating cartridges have an insulation packing, which must, as a rule, be subjected to a compaction process during their manufacture, during which the pressures that must be applied are so high that the sensitive control and/or regulating element may become damaged.
It is known from DE 20 2008 014 050 U1 that this problem can be circumvented in case of a joint arrangement of the control and/or regulating element and the heat conductor in the insulation packing by compaction being carried out at different intensities, which is sufficiently weak in the sections of the heating cartridge in which control and/or regulating elements are arranged to avoid the risk of damage to the control and/or regulating element.
The drawback of this procedure is that the necessity to achieve accurate, location-dependent compaction leads to a high manufacturing effort.
An alternative approach is known from DE 299 20 503 U1. It is proposed there that the control and/or regulating element be provided axially outside the insulation packing and that a heat-conducting tube be provided, which extends over the metal jacket of the electric heating cartridge and in the cavity of which, which is optionally filled by casting, the control and/or regulating element is arranged.
The drawback of this arrangement is that experience has shown that the heat transport that can be achieved in this way is not sufficient, so that, in particular, a prompt response of the control and/or regulating element is no longer guaranteed.
An object of the present invention is consequently to provide a regulated heating device for fluids, which can be manufactured in an uncomplicated manner and in which a prompt response of the control and/or regulating element (control/regulating element) is guaranteed.
The electric heating device according to the present invention for fluids has a tubular jacket surface formed of metal (i.e., a jacket tube consisting of metal—a tubular metal jacket), at least one heating element and at least one control and/or regulating element for the at least one heating element, wherein the at least one heating element and the at least one control and/or regulating element are arranged at least partially within the tubular jacket surface consisting of metal and are embedded at least partially in a powder or granular material present within the tubular jacket surface consisting of metal.
An at least partial embedding in the powder or granular material is defined, in addition to a partial embedding in the longitudinal direction, in which case one section is not embedded, especially also as a partial embedding in the radial direction, in which case the path from the control and/or regulating element to the tubular jacket surface consisting of metal has sections in which the path passes through this powder or granular material and has sections in which it passes through another material, e.g., a powder or granular material possessing different properties.
The control and/or regulating element is used here especially to monitor the temperature. In particular, this term shall also cover sensors, whose measured values are processed by a control arranged outside the electric heating device and are converted into monitoring, control or regulating signals.
In the sense of this patent, the word “tubular” implies any desired cross section, which may also vary in the direction in which the tube extends, i.e., especially circular, rectangular and conically extending cross sections. The tubular jacket surface may also be part of a dummy pipe, i.e., of a pipe with a surface closing its passage.
It is essential for the present invention that at least one heating element is a heating cartridge, a hollow cartridge, a tubular heating element or a coiled tube cartridge, that the powder or granular material is a metal powder or granular metal, and that the at least one control and/or regulating element is electrically insulated from the metal powder or granular metal.
The use of an electric heating element, which use is actually remote because the metal jacket forms the outer surface of the electric heating device anyway, wherein the outer surface of the heating element is formed essentially by a metal jacket, i.e., a metal jacket that is present in addition to the surface of the electric heating device, which implies, in particular, that a heating device is a heating cartridge, a hollow cartridge, a tubular heating element or a coiled tube cartridge, makes it possible in this arrangement to use a metal powder or granular metal as a filler for the metal jacket of the electric heating device.
The development studies have surprisingly shown that because of the joint arrangement of the heating element and a control and/or regulating element electrically insulated against the area surrounding it in a metal powder or granular metal, it can be ensured even without compaction that good heat transfer and short response times are guaranteed. Because of the at least partial embedding of the heat-conducting sleeve in the metal powder or granular metal, heat losses, as they occur in the state of the art, especially in DE 299 20 503 U1, are ruled out, and good heat transfer to the control and/or regulating element is guaranteed, which leads to short response times. As is usual in most cases, the term “metal” also covers, in the sense of this specification, not only pure, elemental metals, but also alloys and intermetallic compounds, especially those in which a metallic bond is present between the constituent atoms.
According to a preferred variant of the present invention, the at least one control and/or regulating element is insulated from the metal powder or granular metal by the at least one control and/or regulating element being arranged within a sleeve, which is likewise arranged at least partially within the tubular jacket surface consisting of metal and is at least partially embedded in the metal powder or granular material present within the first jacket surface consisting of metal.
The sleeve may also be formed, for example, by an insulating tube section or insulating tubing, which may be manufactured especially from Teflon, PTFE, glass silk fabric or a polyimide.
This sleeve is then preferably filled with a powder or granular material, e.g., MgO, which possesses electrically insulating but good heat-conducting properties, which makes it possible to use control and/or regulating elements with electrically conducting parts on the outer side thereof. Other advantageous fillers for the sleeve are, for example, epoxy resin or silicone rubber. The control and/or regulating element can also be permanently embedded in the sleeve by casting with these alternative fillers.
As an alternative, the use of such control and/or regulating element may, however, also be made possible by surrounding the control and/or regulating element with an electrically con-conducting sleeve, which may be formed, e.g., by a heat-shrinkable sleeve.
At the same time, the sleeve represents a shield for the pressure-sensitive control and/or regulating element against the pressure occurring during the compaction, so that the entire arrangement can even be compacted without there being a drastically increased risk of failure because of a possible damage to the control and/or regulating element. Due to the sleeve being provided, lower compaction of the powder or granular material can automatically be achieved during a compaction in the area in which the control and/or regulating element is embedded.
It must be ensured, especially because of the surrounding area, which is formed by the metal powder or granular metal, being conducting, that the control and/or regulating element is electrically insulated in relation to this surrounding area. This can be achieved by the use of a sleeve consisting of an electrically insulating material, which does, however, preferably have good heat conduction, optionally with the use of a cover and/or bottom plate consisting of the same material, but, as an alternative or in addition, also by embedding the control and/or regulating element in electrically insulating filler, especially MgO, which does, however, preferably possess good thermal conduction, in the space within the sleeve.
The suitable, electrically non-conducting materials include especially MgO, ceramic compound, e.g., a cement, silicone rubber casting compound or epoxy resin. Molded parts made of plastic, rubber, silicone, Teflon or micanite may also be used.
Various metal powders or granular metals may be used, aluminum or copper being preferred. The material of which the sleeve consists is preferably a metal, especially copper.
In an especially preferred embodiment of the heating device, the sleeve is adapted to the shape of the heating element such that it is in contact with a surface of the heating element at least in some sections. The direct introduction of heat from the heating element into the sleeve, which results from this, leads to an especially short response time.
It is especially advantageous if there is a flat, direct contact between the heating element and the sleeve, which can be guaranteed especially by the sleeve extending around the surface of the heating element at least in some sections and is especially flatly in contact on a section of the outer jacket of the heating cartridge acting as a heating element, hollow cartridge or coiled tube cartridge or of the tubular heating element acting as a heating element.
The outer surface of the sleeve should be located at the greatest possible distance from the inner side of the tubular jacket surface of the electric heating device, because the heat transfer is, as a rule, poorer through the electrically insulating powder or granular material arranged in the interior space of the sleeve at equal compaction than in case of heat transfer through metal powder or granular metal, and a greater distance from the inner side of the tubular jacket surface reduces the volume in which the material having poorer thermal conduction is present.
The at least one control and/or regulating element is preferably configured as a fuse, platinum measuring resistor, NTC (Negative Temperature Coefficient) thermistor, bimetallic release or as a combination of these elements. It should be noted, in general, that the term control and/or regulating element also covers in the sense of this specification components that represent only a component of a controlling or regulating device.
In an advantageous variant of the present invention, the sleeve is adapted, at least in some sections, to the outer contour of the control and/or regulating element. This is especially advantageous when the control and/or regulating element is highly sensitive, so that the homogeneity and sufficient thermal conductivity of an electrically insulating insulation material, in which it is embedded, cannot be guaranteed. By transforming an electrically insulating sleeve into an exactly predefinable shape, the need to subject the control and/or regulating element to a pressure in the manufacturing process can be eliminated in the first place.
The heating device may, in particular, be uncompacted, but it nevertheless has a rapid response characteristic. As an alternative to such a completely uncompacted heating device, provisions are, however, made in a preferred embodiment of the present invention for the heating device to have, in the axial direction, at least one section, in which a cross section through the tubular jacket extends, extends through both compacted areas and uncompacted areas or through areas with different degrees of compaction. The compacted areas may be formed, in particular, by sections of a heating element already compacted to the desired extent in the form of a heating cartridge, hollow cartridge or coiled tube cartridge. The uncompacted areas may then be formed especially by an uncompacted metal powder or granular metal only filled into the remaining interior space of the metal jacket.
The method according to the present invention for manufacturing such an electric heating device has at least the steps of
The order in which the steps are carried out is preset only in the sense that the particular components to be positioned must, of course, be provided before the positioning and the positioning of the components must take place prior to the filling of the inner volume of the tubular jacket surface consisting of metal or of the tube jacket consisting of metal. The positioning step may also be split, so that the particular assembly unit provided may then also be positioned before the next assembly unit is provided.
The heating element provided is preferably already compacted as desired.
According to a preferred variant of the method, provisions are made for the control and/or regulating element to be insulated against the area surrounding it by being arranged in the interior space of a sleeve such that the control and/or regulating element is electrically insulated against the outer sides of the sleeve.
The control and/or regulating element can be provided such that it is arranged in the interior space of a sleeve such that the control and/or regulating element is electrically insulated against the outer sides of the sleeve especially by using an electrically insulated sleeve without filler, which sleeve is then adapted, preferably by press forming, such that it is adapted to the outer contour of the control and/or regulating element. While the application of pressure to the control and/or regulating element is avoided to the greatest extent possible, the unfilled inner volume of the electrically insulating sleeve can be minimized as a result, which improves the response characteristic of the control and/or regulating element especially in case of temperature monitoring.
As an alternative, the control and/or regulating element, which is arranged in the interior space of a sleeve such that the control and/or regulating element is electrically insulated against the outer sides of the sleeve, may also be provided by the control and/or regulating element being arranged in the interior space of the sleeve and the remaining interior space being then filled with electrically insulating material, for example, with an electrically insulating powder or granular material, e.g., one consisting of MgO. A cautious, controlled compaction may then optionally also be carried out, especially in the latter case, in order to guarantee permanent embedding of the control and/or regulating element.
A third possibility of providing a control and/or regulating element, which is arranged in the interior space of a sleeve such that the control and/or regulating element is electrically insulated against the outer sides of the sleeve, is to arrange the control and/or regulating element in the interior space of the sleeve and then filling the remaining interior space with a casting compound, especially with a casting compound in the form of epoxy resin or silicone rubber.
For control and/or regulating elements that are arranged at electric terminals of the electric heating element, it is advantageous to establish the electric connection between the corresponding electric terminal and the control and/or regulating element before positioning in the interior of the tubular jacket surface consisting of metal.
It may be advantageous in this connection, in particular, to establish this electric connection, then to pull the sleeve over the control and/or regulating element and to subsequently minimize the remaining inner volume either by forming the sleeve or by filling with an electrically insulating material in order to thus ensure that the control and/or regulating element is arranged in the interior space of a sleeve such that it is electrically insulated from the outer side of the sleeve in such a form that is also electrically connected to the electric heating element. The sleeve can then optionally also be connected to a closing plate.
The present invention will be explained in more detail below on the basis of drawings. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
In the drawings:
Referring to the drawings, identical reference numbers are used for identical components of the same exemplary embodiments in all figures.
The control and/or regulating elements 103 are arranged each individually in a respective sleeve 107, which is preferably configured as a copper pipe. It is, however, also possible to arrange a plurality of control and/or regulating elements 103 in a common sleeve 107, in which case it is irrelevant whether the corresponding control and/or regulating elements 103 are connected to the same or different electric terminals 105 of the heating element 102.
The sleeves 107 are configured in the embodiment being shown such that they are in contact by one section with the surface of the heating element 102, enclosing the latter. Due to the control and/or regulating element 103 being arranged within the sleeves 107, damage to the control and/or regulating elements 103 is avoided even in case of a high compaction and rapid response of the control and/or regulating elements 103 is achieved.
The heating element 102, the control and/or regulating elements 103 and the sleeves 107 are all embedded in a powder or granular material, and it should be noted that different powders or granular materials are involved, which it also recognized from the circumstance that the powder or granular material 108 is represented by a different shading in the area within the sleeves 107 than the powder or granular material 109 in the area outside the sleeves 107. Outside the sleeves 107 and the tubular jacket of the tubular heating body 102, there is a metal powder or granular metal 109 to guarantee good heat transport to the control and/or regulating elements 103 and to keep the response time of said control and/or regulating elements low even without compaction or with slight compaction of the electric heating cartridge 100.
By contrast, an electrically insulating filler, which may be configured especially as an MgO powder or granular MgO, is provided within the sleeves 107.
To guarantee strain relief of the contact points 104, the sleeves 107 are equipped each with optional closing plates 110, through which the connection lines 106 are led, and an additional optional closing plate 111, through which the connection lines 106 are likewise led, is provided for closing the dummy pipe. Further, an optional cover plate 112, with which a container, not shown, in which the heating device 100 shall be arranged, can be closed, is also provided on the side of the heating device 100 on which the connection lines 106 exit.
The exemplary embodiment of the heating device 200 according to
The exemplary embodiment of the heating device 300 according to
The exemplary embodiment of the heating device 400 according to
The connection area of the heating device 500, which is shown as a detail in
The exemplary embodiment of the electric heating device 600 according to
The exemplary embodiment of the heating device 700 according to
The exemplary embodiment of the heating device 800 according to
The exemplary embodiment of the heating device 900 according to
In the exemplary embodiment of the heating device 1000 according to
In the exemplary embodiment of the heating device 1100 according to
In addition, it should be noted that in all sectional views with the exception of
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
Number | Date | Country | Kind |
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10 2015 114 886.2 | Sep 2015 | DE | national |